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Astrology And The Sky... Are They The Same?

Guest Post By Athen Chimenti

It makes sense to think of our sun sign as what is reflected by the constellations in the sky, right? If you are a Leo for example, it is perfectly reasonable to believe that the sun was in the constellation Leo during the time of your birth. But what if I were to tell you this is not the case, and that your zodiac sign, as you know it, is based on something else entirely? Welcome to the world of mainstream western astrology, where our signs are not at all based on the actual sky.

Ptolemy astrologyRoughly two thousand years ago, a mathematician, astronomer, and astrologer named Claudius Ptolemy created a system to simplify the complicated task of creating astrological charts. At that time, the sun was rising at the beginning of the constellation Aries during the spring equinox. Aries, as you might know, is very much associated with the same qualities as Spring: action, drive, initiative, etc. The problem he was trying to simplify, however, was a little something called precession. According to a Washington State University astronomy lecture transcript available online, "the phenomenon we call 'precession' was discovered by Greek astronomer Hipparchus when he compared his own circa 200 BC records with older charts. What he saw was that the equinoxes in his day (where the sun's path crosses the celestial equator) were in a different position among the stars than the 150-year-old comparison charts showed. This is due to a gyroscopic wobble of earth's spin axis that takes 26000 years to complete."

What this means is that the sun does not return to its exact position every year. In other words, as time goes on, the sun will no longer be in Aries during the spring equinox. The change is very subtle, roughly only one degree every seventy-two years. So Ptolemy tried to simplify this overly complicated mathematical problem by simply locking the zodiac signs to the dates of the year. This is why your sun sign date is always the same every year. With this new system, every spring equinox, the astrological chart would show the sun at zero degrees Aries.

The problem with this, as you might imagine, is that it is two thousand years later. The zodiac signs are almost a full sign away from where they were when Ptolemy simplified the astrological chart. So what constellation is rising in the sky during the spring equinox today? Well, Pisces. And as time goes on the sun is moving out of Pisces and getting closer to the constellation Aquarius in the spring. Basically, this is the dawning of the Age of Aquarius.

So what does this mean for your mainstream sun sign? Well, nothing really. According to the vast majority of western astrologers if you are a Leo, then you are a Leo. This is because they are using the Ptolemaic system called Tropical Astrology, which is based on the seasons of the Earth instead of the actual sky.

But where was the sun actually at during the day of your birth?

Aries (Apr 21 — May 12)

Taurus: (May 13 — Jun 19)

Gemini (Jun 20 — Jul 16)

Cancer (Jul 17 — Aug 6)

Leo (Aug 7 — Sep 14)

Virgo (Sep 15 — Nov 3)

Libra (Nov 4 — Nov 22)

Scorpio (Nov 23 — Dec 6)

Ophiuchus (Dec 7 — Dec 18)

Sagittarius (Dec 19 — Jan 19)

Capricorn (Jan 20 — Feb 13)

Aquarius (Feb 14 — Mar 9)

Pisces (Mar 10 — Apr 20)


(Sorry, folks. Ophiuchus really is a zodiac sign.)

These dates use the midpoints between the constellations, so if you are within three days of another sign you should consider yourself a blend of both signs. This is known as your true sidereal sign, which uses the real location and size of the constellations in the sky. Still, there's no need to forget about the astrology sign you've always identified as. If someone asks you what your sun sign is, it's totally accurate to tell them your mainstream zodiac sign. However, if you want to know where the sun actually was, you can always check your true sidereal sign.


About the author: Athen Chimenti is a Sidereal Astrologer at Mastering the Zodiac

To see a copy of your true sidereal birth chart along with the location of the other planets such as your Ascendant and Moon, you can use this free online chart calculator:

You can also check out Mastering the Zodiac on YouTube for daily and weekly sidereal horoscopes.


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